cells… part ii
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Cells… part II. Converting Energy. Mitochondria convert sugars and fats to NRG (ATP) with the help of oxygen Cellular respiration Chloroplasts convert sunlight (solar NRG) to chemical NRG Photosynthesis Both have: 2 membranes Their own DNA and ribosomes - PowerPoint PPT PresentationTRANSCRIPT
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Cells… part II
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Converting Energy Mitochondria convert sugars
and fats to NRG (ATP) with the help of oxygen – Cellular respiration
Chloroplasts convert sunlight (solar NRG) to chemical NRG– Photosynthesis
Both have:– 2 membranes– Their own DNA and ribosomes– Ability to grow and reproduce
independently of the cell
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Mitochondria• quantity in cell correlated with
metabolic activity•location of cellular respiration•double phoshoplipid membranes
w/ imbedded proteins- infoldings = cristae- space inside folds = matrix (contains enzymes, DNA, etc)- intermembrane space between cristae and smooth outer membrane
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Chloroplasts•type of plastid
- contain pigments and used for storage in plants- amyloplasts store starch, chromoplasts store orange pigments, etc.
•thylakoids (flattened disks) and grana (stacked thylakoids) •stroma (fluid surrounding thylakoids)- contains enzymes,
DNA, etc.
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Peroxisomes Single membrane Don’t bud from endomembrane
system like lysosomes Metabolism of fatty acids;
detoxification of alcohol (liver) Creates H2O2 as a byproduct of
detoxification Hydrogen peroxide then
converted to water and oxygen by enzymes
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The Cytoskeleton Fibrous network in
cytoplasm– Support for organelles– Cell motility through
interaction w/ motor proteins
– Biochemical regulation- sending of mechanical signals
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Components of the Cytoskeleton Microtubules:
•thickest•tubulin protein•shape, support, transport, chromosome separation• centrosomes, centrioles, cilia, and flagella
Microfilaments :•thinnest;•actin protein filaments; •motility, cell division, shape•includes actin and myosin
Intermediate filaments:•middle diameter•keratin;
•shape, nucleus
anchorage• nuclear lamina
and cell framework
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Centrosomes/centrioles Type of microtubule Centrosome: region near nucleus Centrioles: 9 sets of triplet microtubules in a ring;
used in cell replication; only in animal cells
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Cilia/flagella Locomotive appendages Ultrastructure: “9+2”
•9 doublets of microtubules in a ring •2 single microtubules in center •connected by radial spokes
anchored to a cell by basal body
Move using dynein protein
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Dynein “walking”
Responsible for movement of cilia and flagella
Arms of microtubules “walk” along the adjacent ones, causing a wave-like motion
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Microfilament Movement
Thin strands of actin and thicker strands of myosin allow:
Muscles to contract Amoebas to move w/
pseudopodia Cytoplasm to
“stream” in plant cells
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Cell Wall Only in plant cells primary cell wall produced first middle lamella of pectin
(polysaccharide) forms later– holds cells together
some plants have a secondary cell wall– strong durable matrix– wood – between plasma membrane and
primary wall
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Extracellular matrix (ECM) Glycoproteins
– proteins covalently bonded to carbohydrate
Collagen – 50% of protein in human body– embedded in proteoglycan
(another glycoprotein-95% carbohydrate)
Fibronectins – bind to receptor proteins in
plasma membrane called integrins
– cell communication
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Intracellular JunctionsPLANTS: Plasmodesmata: cell wall
perforations; water and solute passage in plants
ANIMALS: Tight junctions~ fusion of
neighboring cells; prevents leakage between cells
Desmosomes~ riveted, anchoring junction; strong sheets of cells
Gap junctions~ cytoplasmic channels; allows passage of materials or current between cells